Creeping bentgrass (Agrostis stolonifera) is a perennial cool-season grass with a dual identity. It is highly valued in the turf industry for its ability to tolerate extremely low mowing, making it the preferred choice for golf course putting greens. Conversely, when it appears in a traditional lawn, its distinct growth characteristics cause it to be viewed as a troublesome weed. Understanding its appearance requires examining its individual components and how they combine to form a unique structure.
Close-Up Leaf and Stem Characteristics
Identifying a single blade of creeping bentgrass involves looking for specific morphological features. The leaf blades are fine-textured, narrow, and flat, typically measuring between one-eighth and three-eighths of an inch wide. When a new leaf emerges, it is rolled in the bud, and the mature blades are hairless and may feel slightly rough along the edges. The foliage color is often light green or sometimes bluish-green, which allows it to contrast with darker turf species like Kentucky bluegrass.
A defining feature for identification is the ligule, the small membrane found where the leaf blade meets the sheath. Creeping bentgrass possesses a long, membranous ligule that measures from 1 to 6 millimeters in length. This ligule often has a blunt or rounded top and does not have a fringe of hairs. Furthermore, the stem sheath that wraps around the culm is generally smooth and hairless, and the plant lacks auricles, the claw-like appendages found on other grass types.
Defining Growth Habit and Structure
The species name stolonifera references the plant’s creeping growth habit, which is its most distinguishing structural characteristic. Creeping bentgrass spreads primarily through above-ground runners called stolons, which are prostrate stems that can extend over three feet in length. These stolons travel horizontally along the soil surface, forming a dense network.
As the stolons spread, they produce roots and new shoots at their nodes, anchoring themselves and creating new plants. This process leads to the formation of an extremely dense, thick mat of vegetation, often referred to as a thatch layer. This matting is shallow and tightly woven, distinguishing it from grasses that spread using underground rhizomes or those that grow in distinct bunches.
Appearance as a Maintained Turf vs. Weed
The visual presentation of creeping bentgrass is heavily influenced by maintenance and mowing height. When maintained as a turfgrass, such as on golf course putting greens, it is mowed to extremely low heights, sometimes less than a quarter-inch. Under this management, the grass forms an exceptionally uniform, dense, and velvety surface, which is highly desirable for sports turf.
However, when Agrostis stolonifera invades a typical home lawn that is mowed higher, usually between two and three inches, its appearance shifts dramatically. The grass stands out by forming distinct, irregular, puffy, circular patches that are lighter in color than the surrounding turf. This puffiness is caused by the plant’s natural tendency to produce a thick thatch layer, which accumulates rapidly when not kept short.